"MSI have found serious issue with few Gigabyte motherboard
models with chipsets G41, G43 and G45, where the PCI-E x16 in reality
is masked x4 slot. The problem affects all revisions of Gigabyte
EG45M-DS2H, EG43M-SH2H and EG41MF-S2H.Not only that this might limit
the VGA's performance by up to four times but MSI also claim that x4
slots have bad compatibility and if your card is not listed on
Gigabyte's website as supported, than you can only hope that your
card works fine on one of the above mobos. For more take a look at
the picture below."